Mixers and agitators. Extruders.

7. CRUSHING

1. When (heating, having heated) this substance» one

should

be very careful. 3. (Investigated, having investigated,

Investigating) all the

properties of new water, they could understand the mistery

of silvery clouds.

3. The (dissolving, dissolved, having dissolved) materials
may be soluble solids, liquids or gases.

4. later (using, used, having used) in steam boilers, should be free from substances that cause corrosion. ^

5. (Purified, having purified, purifying) the water from the. substance that cause corrosion, we can use it in steam boilers

III. Ask questions on all the parts of the following sentences:

1. Last year a great number of young specialists graduated from our Institute.

2. The new laboratory will be built next year.

IV. Translate the following text using a dictionary. Retell the text:

Comminution by crushing and grinding involves the production of new surface and requires the effective utilization of energy consumed is considerably increased on account of losses due to the elasticity and plasticity of the material and also of course due to friction and the abrasion of the wearing surfaces.

The particle size reduction that one machine can achl-^e is limited. Therefore, the machine required to mak# the final product is often unable to accept the initial.feed so that reduction in stages is necessary. The terra grinding is applied to powder production, and the term crushing to the reduction of coarser materials. There is no hard and fast definition of the limiting particle size for distinguishing between these terms.

Particle-size analysis and the particle shape of a crushed or ground product can be considerably influenced by the choice of machine and by operating conditions. These factors aire of prime importance because they affect the physical properties of the finished product, surface area, chemical reactivity, flow

 

of a fluid through the mass, particle strength, and packing density.In fine-particle sizes, such factors influence th dispersibility and the settling rate ^ in a fluid medium. The yield of useful materials is of vital importance because it directly affects the cost of production..

In the first stages pf reduction by crushing, there is a choice between those machines that reduce by compression between two faces and those that reduce by impact. In each case, there is also some reduction by attrition, but the particle-size distribution produced by impact and by attrition shows rather similar characteristics.

For the primary reduction of a mined material, the jaw crusher is well^ established, Aut the gyratory, cru-isher is preferred where the^higher capacity is ^^iffifified. Both are compression crushers that reduce the material to a piece size related to the crusher settling. Both types of crusher are suitable for intermediate stages of reduction.

Jaw and roll crushers are suitable for fine-crushing modest quantities but the gyratory crusher can reduce larger tonnages.

4.

5.

6.

7.

8.

9.

10,

11,

12,

13.

14,

15.

16.

17,

18,

19 20

grinding -дробление, размалывание, растирание

utilization - использование

to consume -потреблять

friction -трение

abrasion -истирание, абразивный износ

to reduce -уменьшать reduction -уменьшение

feed - подача (материала, сырья)

density - плотность

settling rate - скорость оседания

fluid medi;m:i - жидкая среда

yield - выход (продукции)

face - поверхность syn:surface

impact - толчок, удар, столкновение

attrition - трение

jaw crusher - щековая дробилка

gyratory crusher - конусная дробилка

roll crusher - валковая дробилка

related to - связанный с

settling - настройка, установка; регулировка

tonnage - тоннаж

 

Commentary                             ,,

1. ... on account of losses due to the elasticity and
plasticity of the materiai - ... за счет потерь,
обусловленных упругостью и пластичностью материала

2. due to - обусловленный, вследствие

Answer the following questions

 

Words and word combinations:

1. comminution -измельчение

2. crushing - дробление, раздавливание

3. crusher - дробилка, дробильная установка, мялка

 

1. What does comminution by crushing and grinding involve?

2. What does this process require?

3. Why is the total energy consumed considerably increased?

4. Why is the reduction in stages necessary?

5. What is the term grinding applied to?

6. What is the term crushing applied to?

7. What factors effect the physical properties of the finished product? What else do they effect?

8. Why is the yield of useful material of vital importance?

9. What two types of machines for crushing do you know?

10. What types of crushers do you know? What are they suitable
for?

 

Exercises I. Translate the following sentences into Russian, mind the Participle:

1. The products produced were of high quality.

2. The method involved depended on a number of factors described earlier.

3. The experiments carried out in our laboratory resulted in many new investigations in the field of ceramics.

4. Hydrogen burns readily in air and the product formed la water.

5. There are only few elements not attacked by oxygen.

6. Radioactivity is the property uninfluenced by any known catalyst.

7. The problem discussed is of great importance for the
development of chemical engineering.

II. Translate the following sentences paying attention to passive constructions:

1. This law is generally spoken of as the Second Law of
Ther-aodyaamlcs.

2. This problem will be dealt with in a number of
articles. 3. The rate of a reaction is influenced by many
factors. 4. Sold is not effected by air.

5. Particle - size analysis of a crushed product can be considerably influenced by the choice of machine.

6. This scientist's report is being waited for with great interest.

7. Unlike iron, cobalt is not attacked by air and water.

8. The state of water but not its composition can be
affected by the process of heating or cooling.

9. Shall we be informed about the conference in time?

10. When the students arrived at the plant, they were
shown modern chemical apparatus.

8. GRINDING

There is a wide variety of grinding equipment and systems to suit different materials and conditions in the requirements of many industries. Hammer mills ring-roll mills, tube mills and ball mills, each have their characteristic features and may be combined with various systems of powder■classification. Many difficult materials in the chemical process industries, such as agglomerates, filter cake, and centrifuged products can be ground and dried simultaneously, and cooling arrangements may be used when grinding heat-sensitive materials. Caleiners and machines for mixing and blending can be incorporated in a common system. Specialized plants are designed to meet the requirements for deducing metallic and non-metallic ores, phosphates, sulfur, barytes and other raw materials for the chemical and plastics industries. Sometimes/ , the final stage of crushing and the preliminary stage of// grinding are economically combined into one operation. "*

Impact crushers can be used to combine crushing and grin­ding, in one operation^^These machines offer the lowest capital cost of any grinding mill. Hammer speeds of 4,000ft/min. will suffice for a course product, but upwards of 15,000 ft/min, may be required for fine grinding. With different forms of

crushing chambers, grinding elements and discharge screens, they can be built to handle and reduce almost any material that is not too abrasive. They can be adapted for wet crushing and grinding to produce a slurry, in this way serving an additional purpose, but there is some loss of machine capacity and an increase in power consumption when the machine is used in wet operations. They are used for grinding and classifying non-mejallic minerals and dry chemicals to a fineness ranging from 800 to 35 microns with a high degree of uniformity.

I/Grinding is effected from the action of rollers running inside a horizontal stationary ring. The machine is used for grinding chalk clays, and slate, lime and limestone products; coal and graphites talc and resins, pigments, lead oxides, and so on. It lends itself for. grinding in a controlled atmosphere* For example, because sul-

 

fur is highly flammable, inert gas is introduced when grinding it. Again, when grinding phenol-formaldehyde resins, refrigerated air la introduced to prevent softening of the resin.

Commentary

отвечая

1. ... in the requirements of many industries
требованиям многих отраслей промышленности

2. ft/min (feet per minute) - футов в минуту

3. ranging from... to - в пределах от ... до

14. slurry -суспензия, пульпа

15. power consumption - потребление энергии
16.- fineness - мелкозернистость, тонкость
17.uniformity - однородность

18. roller - валец, ролик, валок

19. ring - кольцо, обод, хомут, обойма

20. clay - глина

21. slate - сланец

22. lime - известь

23. resin - смола

24. to lend itself - быть пригодным

25. sulfur - сера •

26. softening - размягчение

Answer the following questions

Words and word combinations :

1. to grind - дробить, молоть
grinder - дробилка

grinding - дробление, измельчение

2. to suit - подходить, годиться

3. mill - мельница, дробилка hammer mill - молотковая мельница ring-roll mill - кольцевая роликовая мельница tube mill - трубная мельница

ball mill - шаровая мельница roller mill -вальцевая мельница

4. filter cake - осадок после фильтрования ■

5. heat-sensitive -термочувствительный

6. calciner - обжигательная печь

7. mixing = blending - смешивание

8. to meet the requirements - отвечать требованиям

9. to reduce -уменьшать, измельчать

 

10. crushing -дробление, раздавливание, измельчение crusher - мялка,дробилка

11. upwards - больше, выше, свьшіе

12. chamber - камера

13. discharge screen - выпускной грохот

 

1. What types of mills do you know?

2. What materials in the chemical process industries can be ground and dried simultaneously?

3. What materials can be reduced at specialized plants?

4. Can crushing and grinding be combined into one operation? 5. Can impact crushers be used in wet operations?

 

6. What are roller mills used for?

7. What parts does a roller mill consist of?

8. What materials can be ground by means of в roller mill?

Exercises

I. Open the brackets choosing the correct form of the Parti-Spies. Translate the sentences into Russian:

l.A positively {charging, cbarged) particle having the mass.

 

 

2. The scientist found that X-rays (producing, produced) were complex.

3. Oppositely (charging, charged) particles exert forces of attraction on one another.

 

4. The work (doing, done) by these research-workers resulted in many new discoveries.

5. The investigation (following, followed) by many experiments was of great importance.

6. The nuclei (forming, formed) in this reaction are unstable.

7. When (working, worked) in the lab the students carried out many experiments.

8. The student (translating, translated) the article knows English very well.

II. Use the following sentences in all the forms and
tenses adding suitable adverbial modifiers where
necessary:

1. People employ glass for many purposes.

2. Stainless steel is widely used in chemical
machinery.

III. Translate into Russian paying attention to the
word "for":

1. Our age is called the age of atom, for we use the atom for various purposes. '

2. For a long time scientists were not able to discover the secret of the atom.

3. Hydrogen is widely used, for it contains a large amount of chemical energy.

9. SCREENING

Screening is the mechanical separation of particles on the basis of size. This separation is accomplished on a scree-

ning surface with uniformly sized apertures. Particles larger than these apertures are rejected and pass over the surface, while those smaller are accepted and pass through. Many terms are applied to this operation including: sifting, sieving and separation.

Most commonly, screens are used in conjunction with size-reduction operations, but they are found in other applications such as washing, dewatering, desliming, dedusting, etc.

Screens are used for processing a wide variety of materials, .ranging from the fineness of talc up to boulders as large as б by 6 ft. Openings in screening surfaces may be as small as 0,005 in, or as large as 8 or 10 in, with some as large as 18 in.

Screens find application in many Industries, including those producing sand and gravel, crushed stone, minerals, ceramics, coal, chemicals, petroleum, and other products.

A screen consists of a plane surface in which,there are apertures or holes of a given size. These holes may be square, rectangular, round or slotted-intermittent or continuous. The surface is usually supported at the edges by a rigid frame to which a vibratory force is applied.' In some screens the force may be applied directly to the screen surface.

Materials to be sized are placed on this surface while it is in motion. For practical considerations, the surface is often inclined, or the line of action of the driving force is inclined slightly from the vertical so that a horizontal component will be available to move the particles across the surface. This permits each particle to be presented to a number of openings, and also makes room for additional feed material to be placed on the screen.

Particles that are much smaller in all dimensions than the openings usually pass through-rapidly and do not travel far across the surface. Particles larger than the openings in two or more dimensions will not pass through, and travel across the surface and pass over the discharge point. When particles are smaller than the openings in two dimensions, they may pass through if their narrow aspect is presented to the opening. The more times they are presented, the greater the probability

 

that they will be accepted and pass through. As the size of the particles more nearly matches the size of the openings, the probability of rejection increases.

Screening efficiency is not measured in terms of work, but by a far different set of criteria. For most average screening operations, screening efficiencies of 85 to 95 % are acceptable.

 

14. to make room - дать /уступить/ место

15. additional - дополнительный

16. discharge point - место выпуска

17. to match - подходить, соответствовать

18. to reject - отбрасывать rejection - отбрасывание

19. efficiency - производительность

20. average - средний

 

Commentary

1. ranging from ... to - в пределах от ... до

2. as large as 6 by 6 ft - (величиной) до 6x6 футов

3. so that a horizontal component will be available to move the particles across the surface - так что горизонтальная часть будет способствовать продвижения частиц по поверхности

Words and word combinations

Answer the following questions

1. What is screening?

2. Where -is screening accomplished?

3. In what operations are screens used?

4. What are dimensions of openings in screening surfaces?

5. Where do screens find application?

6. What parts does a screen consist of?

7. What may the holes of a screening surface be?

8. What particles pass through the holes of a screening surface, and what particles are rejected?

 

1. 2. 3. 4. 5. 6. 7.

10 11 12 13

screen - сито, грохот screening - грохочение

aperture - отверстие syn.: opening, hole

at least - no крайней мере dimension - измерение

sifting - просеивание, грохочение

in conjunction with - вместе с

dewatering - обезвоживание, удаление воды

boulder - глыба, крупный кусок

rectangular - прямоугольный . slotted - шлицованный . frame - рама, основа . to incline - наклонять . driving force - движущая сила

Exercises I. Translate the following sentences, paying attention to the Infinitive:

1. Newton was the first to discover the basic laws of motion.

2. The problem to be solved requires some experiments.

3. Materials to be sized are placed on a screening
surface.

4. To slow down the oar means to decelerate its motion on the road.

5. To make the car go faster, we press down on the accelerator

 

6..The question to be answered requires some time.

7. Where is the article to be translated into English?

8. The material to be used was examined in our laboratory.

9. Where is the mixture to be heated?

10. She was the last learn the news.

II. Translate the following sentences into Russian;

1. The stronger the acid, the greater is the tendency to lose protons.

2. The faster the object moves, the greater is the air resistance.

3. The greater the number of free electrons is a
substance, the better that substance is a conductor of
electricity.

4. The earlier we get up, the fresher we feel.

5. The more the students read Englisg, the better they speak.

6. The sooner we finish our work, the earlier we can go home

10. HEAT EXCHANGERS

A heat exchanger, in the narrow sense, is a vessel in which an outgoing processed, hot liquid transfers some of its heat to an incoming cold liquid to be processed. An alternative term is heat interchanger. The amount of heat so transferred is not lost to the process but is used over again; its equivalent need not be supplied by new fuels it may be considered as cycled heat. Hot gases end vapors similarly may be enabled to pass part of their heat to the incoming cold liquid. A heat exchanger, ' .still in the narrow sense, may also transfer in the opposite direction, for example, in an interchanger in which an outgoing cold gas takes up the heat of the incoming warmer gas, as in a liquid-air plant. In the widest sense, a heat exchanger is any device at all which makes possible a heat transfer from one fluid to another through a containing wall.

For the moment, let us consider the heat exchanger in which an outgoing hot liquid transfers its heat to an incoming cold one. One type which is widely used, largely because of its compactness, is the "shell-and-tube" type, consisting of a cylindrical shell within which lies a bundle of tubes, either straight or coiled in the form of U-tubes. Another type is the multitube type, containing numerous (perhaps 40) separate tubes, within each of which an inner tube carried the cold liquid.

Shell-and-Tube-Heat Exchangers. For the shell-and-tube exchanger, there is no rule which dictates which liquid should travel through the shell and which through the tubes: the selection depends upon a number of considerations. In general, the hot liquid should travel through the shell and the cold liquid in the tubes. A-wide variety of further considerations will govern the final selection. Thus, in an exchanger for a caustic solution which is to be built partly of nickel, and partly of steel, the tube side would be selected for the travel of the caustic solution, because less nickel would be required on that side to provide all nickel passages.

Another example' would be that of a dirty fluid to be treated with a clean liquid. The dirty liquid would be sent through the tubes, irrespective of temperatures, for the tubes may be cleaned on their inner side comparatively easily.

Multiple-type Exchangers. Another type of heat exchanger for liquids is the multitude type, in which each inner tube with its outer tube forms a separate unit, and many units (as many as 40) are combined. The flow of the liquids through all the tubes is truly countercurrent. The advantage possessed by this type is that each unit acquires a definite temperature essentially uniform for the single unit, so that once the apparatus is operating, the strains are constant. The multitude exchanger is not adapted to the handling of large volumes of liquids.

 

Words and word combinations;

1. to process - обрабатывать

2. interchanger - обменник

heat interchanger - теплообменник

3. to transfer - передавать, переносить

4. over again - много раз, повторно

5. to cycle - совершать цикл

6. to pass - передавать

7. plant - I) завод, фабрика, 2) силовая установка, агрегат

8. to contain - вмещать, содержать в себе

9. because of - из-за, вследствие

 

10. shell -корпус, остов, оболочка

11. tube - труба

12. bundle - пачка, связка

13. to coil - наматывать; свертывать

14. selection - выбор

15. solution - раствор

16. passage - прохождение

17. to treat - обрабатывать

18. irrespective - независимо от

19. multiple - составной

20. unit - блок

21. as many as 40 - до сорока (блоков)

22. countercurrent - противоТ'ок

23. strain - напряжение

Answer the following questions;

1. What is a heat exchanger?

2. For what purpose are heat exchangers used?

3. What types of heat exchangers do you know?

4. What does the "shell-and-tube" heat exchanger consist of?

5. Which liquid should travel through the shell and which through the tubes? Is there a strict rule for it?

Give some

examples.

6. How many separate units are combined in a multiple-type exchanger?

7. What tubes does each separate unit consist of?

8. What is the advantage of a multiple-type exchanger?

Exercises

I. Translate the following sentences. Mind the functions of the infinitives:

1. The problem to be studied is of great importance for the development of chemistry.

2. To separate iron from sulphur is an easy task»

3. The function of a boiler is to transfer heat to the weter in the most efficient manner. »

4. Mechanization is to be distinguished from more primitive . tool using.

5. Lomonosov is known to have been one of the greatest men of science.

6. We know the thermometer to be an instrument for measuring temperature. "

7. When a structure or a machine is to be built, suitable materials are to be chosen for the parts.

8. Silicon is said to pla.7 an important part in the inorganic world.

9. To dissolve rubber, benzene is used.

 

10. Water to be used for drinking should be thoroughly purified.

11. Gold was probably one of-the first metals to attract the attention of men.

II. Ask questions on all the parts of the following

sentences?

1. Liquid products from the plant can be skipped by

rail, truck or pipeline.

 

2, The engineers of our plant constructed a new electrical de-vise last year.

11. DRIERS

Drying is one of the most frequently encounted chemical engineering operations. Drying generally signifies the removal of liquid from a solid by evaporation, although gases are also dried. Mechanical methods for separating a liquid from a solid are not generally considered drying, although they often precede a drying operation.

Driers may be classified in several ways. The two most useful classifications are based on:

1) the method of transferring heat to the wet solids;

2) The handling characteristics and physical properties of the wet materials.

The first method of classification reveals difference in drier design and operations, while the second one is if most useful in the selection of a drier for a given application.

According to the first method of classification driers are: direct, indirect and mechanical.

In a direct drier the heat is supplied to the wet solid by means of direct contact with hot gases, the gases also carrying away the vaporized liquids.

In an indirect drier the heat is supplied to the wet material from, heated surfaces in the drier, such as tubes or jackets.

In mechanical driers the heat required for drying is generated by mechanical friction.

Further, a drier may be designed for batch or continuous operation. Direct and indirect driers may be batch or continuous.

The second method of classification of driers considers the characteristics of the materials being processed: liquids.

slurries, pastes, free-flowing powders, granular or crystalline solids, continuous sheets (paper, plastic sheets), discontinuous sheets (wallboard, leather) etc. Direct Driers. Direct driers may use air, inert gas, superheated vapooar, or products of combustion as the heating medium» Combustion gases, however, are seldom used la polymer plant because of possible product contamination.

There are many types of direct driers. One of them is a rotary drier. Rotary driers have been the most popular in polymer production. They consist of a revolving drum through which both the -material and gas pass. Gas, concurrent or countercurrent with the polymer, can be introduced at either end of the cylinder. Solids move on through the drier by the effect of the ■ slope (gravity), the rotation of the cylinder, and gas flow (in the case of cocurrent units). Internal scoops, blades, or lif-ters - are provided for better contact between the hot gas and

the solids. Baffles and dam rings are also available to retard the forward motion of the solids, and to increase residence time (-5 to 20 min is common) . The length of the cylinder may vary from four to ten times its diameter; driers having a diameter up to 12 ft. are not uncommon for large polymer plants. This type of drier is common in polystyrene processes, among others.

Commentary Gas, cocurrent or countercurrent with the polymer... -газ, движущийся в а?ом же направлении, что и полимер, или в противоположном

1. drier - сушилка

2. to precede - предшествовать

 

характер обработки

3.

4. 5. б. 7.

handling characteristics

to reveal - обнаруживать

tube - труба, трубка

jacket - стенка цилиндра

friction - трение

to design - ЗД.: предназначаться

batch operation - периодическое действие

16,

17,

18,

19,

20,

wallboard - стеновая плита

combustion - сгорание

contamination - загрязнение

revolving drum - вращающийся барабан

by the effect of - под воздействием

scoops = blade - лопасть, лопатка

baffle - перегородка, турбулизатор потока

dam - запруда, перемычка

ring - кольцо, обруч, ободок

to retard - замедлять

residence time - время (длительность) пребывания

Answer the following questions:

1. What does drying generally signify?

2. What are the two most useful classifications'of driers based on?

3. What driers do you know according to the first method of classification?

4. What is a direct (indirect, mechanical) drier?

5. What does the second method of classification of driers consider?

6. What do direct driers use as the heating medium?

7. What does a rotary drier consist of?

8. How do solids move on through a rotary drier?

9. For what purpose are baffles and dam rings used?

10. How may the length of the cylinder vary?

Exercises

I. Translate the following sentences paying attention to the meaning of the word "time" :

1. There was- a time when people knew nothing about polymers.

2. One of the cylinders is four times as large as the other one,

3. In those times lightning was a subject for
legends.

4. At times he comes to visit us.

5. Three times four .is twelve.

6. What time is it? I think it is time to stop the motor.

7. We cannot test this drier at a time.

II. -Translate the following sentences. Mind the
Absolute Par-, ticiple Construction:

1. D.I.Mendeleyev being a great chemist, his name is
well known not only in the USSR but also abroad.

2. Hydrogen is the simplest substance, atoms of
other elements having a more complex structure.

3. The properties of the element having been
discovered, it was much easier to use it.

4. Moscow and London have different climate, the
average temperature being higher in London than in
Moscow.

5. Our students studying chemistry, many experiments are made at the laboratory.

6. The settlement occupies a large area, the houses being built along the river.

7. Radioactivity having been discovered, science
made great progress in atomic physics.

8. London is divided by the river Thames into two
parts, the East-End being inhabited by the working
people of the city.

III. Ask questions on all the parts of the
following sentences 8

1. Some new driers were developed in the USSR last year.

.2. They carry on their research work in the laboratory of ana-

 

lytlcal chemistry.

IV. Translate the following text using a dictionary!

Evaporators

Evaporation is the removal of solvent as vapour from a solution or slurry. The vapour may or may not be recovered depending on its.value. The end product may be a solid, but the transfer of heat in the evaporator must be to a solution or a suspension of the solid in liquid. Evaporators are similar to reboilers of distillation columns except that no attempt is made to separate components of the vapour.

There are three principal elements involved in evaporator design - heat transfer, vapour-liquid separation, and energy utilization. The units in which heat transfer takes place are called heating elements or calandrias.

Heat transfer is the most important factor in evaporator design since the heating surface represents the largest part of evaporator cost.

There are many types of evaporators used in industry. The largest user of evaporation equipment is the pulp and paper industry. This industry produces the largest quantity of evaporators.

12. FILTRATION. FILTERS

Filtration, In many industrial processes it is necessary to separate finely divided solid materials

from liquids. The process of filtration consists in passing the liquid through a porous medium, which retains the solid particles. In some cases the recovery of the solid material is the main) object; in others the filtration is done for the sake of 44

purifying the liquid. Many types of filter are in use today. They differ in respect to the various materials which are available for filtration, and the construction of the apparatus in which these are applied.

The mixture to be separated is called the slurry: the fluid that passes through the septum is called the filtrates and the septum is called the filter medium. When the separated solids accumulate in amounts that visibly cover the medium, they are called the filter cake or simply the cake.

Filter media are manufactured from cotton, wool, linen, silk, glass fiber, porous carbon and other solids, rayons and other synthetics, porous rubber, etc.

Filters. Filters used in chemical processing are classified into two distinct groups: continuous and intermittent.

Continuous filters. Filters that operate without Interruption for weeks to months are classified as continuous filters. The main types are the rotary drum and disk filters and various horizontal designs.

Rotary drum filters are the most widely used continuous filters in the'chemical process industries. The design provides means for concentrating slurry solids to dry (moist) cakes, washing solubles from such cakes when required, and producing a clarified effluent.

Many design configurations have been developed to utilize most effectively the basic principle for the varying filtration characteristics of slurries, ranging from extremely fine particles (1-1 mm) to very coarse particles (50 - 150 mm) and from thin, sticky cakes to thick, fairly dry sludges. These filters are used in some form in practically every process operation involving slurries where solids must be recovered from the liquor for further processing.

It is estimated that over 25 000 rotary drum filters are in operation worldwide at present.

Rotary disk filter is a version of the rotary drum
filter. A series of parallel disks provides vertical
filtering surfaces in place of the cylindrical surface
on the rotary              ' -

drum. Thus, the rotary-disk unit provides more filter area (up to 3.5 times) than a drum type.

When the filtering surface operates in a horizontal plane, the filter is designated as a horizontal type.

Intermittent filters. Filters whose continued vibration is limited by their solid-collecting capacity are known as intermittent filters. Their cycle must be interrupted periodically when the solids accumulation has to be discharged.

Words and word combinations :

1. medium - среда, вещеса?во filter medium - фильтрующая среда

2. recovery - восстановление

3. for the sake of - ради, для

4. to purify - очищать

5. in respect to - в отношении

6. mixture - смесь

7. slurry - суспензия

8. septum- септа, перегородка

9. to accumulate - накапливаться
accumulation -накопление, скопление

10. filter cake - осадок после фильтрования

11. continuous filter - аналоговый фильтр intermittent filter - импульсный фильтр

12. interruption - остановка, перерыв

13. rotary drum filter - ротационный барабанный фильтр

14. means (pi.) - средство, способ

15. soluble - зд.: растворимый компонент

16. clarified effluent - очищенный поток

17. sticky -липкий, клейкий

18. sludge - отстой

19. unit - агрегат

20. to designate - определять

21. to discharge - разгружать

Answer the following questions :

1. What does the process of filtration consist in?

2. What is the purpose of the filtration process?

3. What is called the slurry (filtrate, filter medium, filter cake)?

4. What are filter media manufactured from?

5. What two groups of filters do you know?

6. How do continuous filters operate?

7. What does the design of a rotary drum filter provide?

8. What do you know about the varying filtration characteristics of slurries?

9. How many rotary drum filters are in operation worldwide' at present?

 

10. What do you know about the design of a rotary disk filter? ■

11. How do intermittent filters operate?

Exercises I. Translate into Russian paying attention to the word

1. It was known long ago that oil could be used as a raw materi-al.

2. As the evaporation continues, the temperature of the water gradually drops.

3. He works a£ a turner.

4. This experiment is as interesting as the previous one,

5. As this question is of outmost importance, we shall discuss it at once.

^' As to me I prefer to spend my vacation in the South. 7. Filters that operate without interruption are known as continuous filters.

II. Translate the sentences into Russian. Mind the . Gerund and Gerund Groups:

 

1. Solid bodies have the property of keeping their shape.

2. Upon being heated, the molecules begin moving very quickly.

3. Without being treated this substance cannot be used.

4. At last our research-workers succeeded in getting good results.

5. The teacher insists on carrying out this experiment in our laboratory.

6. Upon carrying out a number of experiments oar students solved many interesting problems.

7. Heating the wire from 0° to 100° increases the
resistance

approximately by 4 0%,

8. They finished looking through the papers as soon as they had found the article concerned.

9. The engineer told us about his having invited to that research institute.

10. She engineer having constructed a new type of a filter
was

not known to us,

11. We know of the new laboratory having been built in our
institute. 12. We were surprised at Peter's having got an
excellent mark in physics.

III. Use the following sentences in all the forms and tenses adding suitable adverbial modifiers where necessary:

1. Many new enterprises are built in Siberia.

2. Our engineers develop new devices.

13. CENTRIFUGES

Centrifuges are machines used for solid-liquid separation. Process requirements for a solid-liquid separation are maximum clarification of liquid and minimum cake moisture.

Sedimentation centrifuges. These remove solids from liquids by causing solid particles to "settle" through the liquid radially toward or away from the centre of rotation. If the solids are less dense than the liquid they move inward to the liquid surface. If they are more dense than the liquid they "sink" outward and deposit on the inner surface of the bowl, from which they are removed manually, or mechanically by a conveyer or a knife. In some centrifuges heavy solids are not allowed to deposit on the bowl wall but excape continuously through nozzles as a thick slurry. Sedimentation centrifuges are usually comparatively small in diameter and may operate at extremely high speeds.

Most sedimentation centrifuges operate continuously, or nearly so, with respect to the feed and liquid discharge. In some applications it is necessary to interrupt the flow periodically to permit removal of accumulated solids. This interruption may be as long as 30 min or as a few seconds. In many designs clarified liquid and concentrated solids are both discharged continuously, so that the machine may operate for many hours or days without interruption.

The sedimentation centrifuges having many important characteristics resulted in their being widely used in chemical process industries. There are many types of cedimentatiom centrifuges, a solid-bowl centrifuge being one of them.

Solid-bowl centrifuges. This is a continuous-sedimentation unit, commonly called a decanter. It has no filter medium; separation is effected by density difference.

These devices are available in both horizontal and vertical types, their mode of operation being similar. They consist essentially of two concentric rotating elements surrounded by a stationary housing. The outer element is a solid-bowl tapered at one end; the inner element is a screw conveyer shaped to closely fit the bowl contour.

Slurry entering the cylindrical portion of the bowl is acted upon by centrifugal force, which separates the solids from the liquor and drives them against the bowl wall. The rotating conveyer - operating at a slightly different speed om

that of the bowl - conveys the solids up through the conical portion of the vessel and discharges them as cake product. Clarified liquor continuously discharges over adjustable weirs from the other end of the bowl. Various types of bowl configurations are available to achieve good solids dryness and clarity of liquid.

Limited to solids that can be readily conveyed, these machines cannot handle some soft, slimy products, and viscous slurries reduce capacity. The units can, however, process a wide range of particle sizes - from 5 to 2,000 microns, depending on density and available G forces.

to discharge - разгружать

10. removal - удаление, устранение

11. housing - корпус, коробка

12. screw conveyer - шнековый конвейер

13. portion - зд.: часть /цилиндра/

14. adjustable -^ регулируемый

15. weir - водослив

16. slimy - илистый

17. unit - агрегат

 

Conmentary

1. ... shaped to closely fit the bowl contour - ... форма которого /конвейера/ соответствует контуру цилиндра

2. with respect to - в отношении, что касается

3. farces = gravity forces - силы тяжести

Words and word combinations

cake - осадок /после центрифугирования/

sedimentation - оседание, осаждение

to settle - оседать, осаждаться

bowl - чан, резервуар, цилиндр solid-bowl centrifuge -сплошной цилиндрический декантер

5. to deposit - осаждаться, давать осадок

6. nozzle - выпускное отверстие slurry - суспензия, пульпа feed - подача, питание discharge - выход, сток

Answer the following questions:

1. What are centrifuges?

2. What are process requirements for a solid-liquid separation?

3. How do sedimentation centrifuges remove solids from liquids?

4. How are solids removed from the inner surface of the bowl?

5. How do sedimentation centrifuges operate?

6. What is a decanter?

7. What does a solid-bowl centrifuge consist of?

8. How does a solid-bowl centrifuge operate?

9. What products cannot be handled by solid bowl centrifuges?

Exercises I. Translate the following sentences paying attention to the meaning of the words "cause" and "both" :

1. Capitalist system is the cause of unemployment.

2. Heat causes many chemical changes in substances.

3. The increase in motion causes the molecules to collide with each other.

4. Change in air pressure is the chief cause of winds.

 

5. What causes a cyclon, and what does it gauge in the
open sea?

6. Both Lomonosov and his friend Rihman worked at atmospheric electricity. Both of them made experiments on that subject.

7. Both above and below 4 °С the density of water decreases.

 

8. Both substances were examined before solving.

9. We wrote to them both.

II. Translate the following sentences paying attention to:

a) the Absolute Participle Constructions and

b) Gerundial Constructions :

1. The equipment having been received, we began the
experiments from the very beginning.

2. An architect designs the building, a civil engineer providing for its construction.

3. The temperature rising, the bodies expand, their volume increasing.

4. There are many good conductors of electricity, silver and copper being the best of all.

 

5. The elements having been arranged in the Periodic Table, it became easier to predict new elements.

6. Germanium was predicted by Mendeleyev the German scientist Winkler discovering it seventeen years later.

7. Your reading English articles on your speciality will
help you, to mastering English.

8. We know of S.V.Lebedev's having made the first
synthetic rubber in the world.

9. S.V.Lebedev's having obtained synthetic rubber was very
important for our industry.

10. Plants are useful sources of energy thanks to their storing the sun's radiation in chemical form.

11. We were informed by the radio of a new spaceship having been launched into orbit.

12. Most metals may readily be recognized by their
metallic lustre, when polished, and by their being good
conductors . of heat and electricity.

13. The workers succeeded in completing the
construction of the plant in time because of their
having introduced new methods of work.

14. Before the Revolution few people knew of
Tsiolkovsky's working at the problem of space flights.

III. Ask questions on all the parts of the following sentences!

1. A new experiment was made in our laboratory last
week.

2. Peter'e brother has been working at the car
factory for five years.

IV. Translate the following text using a dictionary:

AUTOMATION

"Automation" is a new word for a new purpose. Ordinarily automation is any Improvement in the control of some activity or process by non-human, i.e., automatic; means, but sometimes the term is defined more narrowly. Recent steps in automation have followed each other with unusual speed.. Many people are surprised to learn that in industries like chemical and oil-refining entire processes have become very nearly automatic

Electronic computers are becoming very good , at routine clerical work in offices and factories.

Automation has many sides. It includes, for example, mechanical equipment for handling and assembly. Machines of this kind are automatic In that they do the actual work on their owe; the operators only watch them and correct them whenever they go wrong - when, for instance, tools wear out.

But automation can also - mean automatic control of processes and machinery, and this' is a very different thing from mechanization, though the two go together. Control is necessary in a vast number of processes in order to maintain the quality of a product when the operating conditions, such as tem-

 

perature and pressure, change from time to time.

In moat processes, there is a Deed to mix two different liquids, or a solid with, a liquid, or a gas with a liquid. In; order to best accomplish this, a rotating mixer is often used. Some of the duties required of such equipment! heat transfer, chemical reaction, crystallization, leaching, gas dispersion and absorption, fermentation, hydrogenation, and solids suspension. Several types of mixers^are available for these tasks.

Of all the rotating equipment mixers are the least susceptible to scientific calculations. Their selection requires close cooperation between vendor and user, especially for new-type processes. Mixer manufacturers generally have laboratories available for determining the best type of mixer in combination with the tank or vessel required for a process...

When deciding whether a mixer should be top-entering/ bottom-entering, or side-entering, several factors have to be considered. Is there enough headroom available? Are solids to be suspended from the bottom of the tank? Would the material being mixed prove dangerous to personnel if a lesk occured? This would preclude the Use of a bottom-entering mixer or side-entering mixer unless very special precautions were taken with respect to seal leakage.

Unless vortexing is desired, baffles should be used, especially for reactor-type vessels. For critical services in continuous operation, steady bearings should be avoided, since they are normally a maintenance item. An overhung shaft of large diameter can be used, but in this case the physical weight of the shaft must be considered.

There are batch and continuous mixers.

The Farrel Continuous Mixer. This type of mixer ,1s widely used in polymer production. The mixer takes ingredients into one end, mixes them, and discharges them from the other end continuously.

Discharge from the mixer is in the form of a thick ribbon that can be-handled as such, or guillotined into blocks. The machine requires a second-stage device to produce a final product, since it does not develop sufficient pressure to extrude the polymer through a die. This second stage is usually a single-screw extruder equipped with a die.

The single-screw extruder is basically a drag pump that conveys and forces the polymer through a die. The die Bay be provided with a slot for sheet extrusion, or with holes for standing or face cutting.

Commentary

1. ... since they are normally a maintenance item -... так как они /шурболизаторы потока/ представляют собой детали, часто требующие текущего ремонта

Words and word combinations :

1. mixer = agitator - мешалка, смеситель

2. leaching - выплачивание

3. hydrogenation - гидрирование

4. susceptible - поддающийся

5. tank - бак, цистерна

6. vessel - резервуар, сосуд

7. headroom - габаритная высота

8. bottom - дно

 

9. leak = leakage - утечки, просачивание

10. to preclude - предоа?враш;ашь

11. precaution - мера предосторожноса?и

12. with respect to - в отношении

13. seal - заделка, запайка

14. vortexing - взвихривание

15. baffle = bearing - 'турболизатор потока

16. overhung shaft - свободно установленный вал /стержень/

17. batch mixer - мешалка периодического действия continuous mixer - мешалка непрерывного действия

18. ingredient - составная часть, ингредиент

20 21 22 23 25

19. to extrude - выталкивать, выдавливать
die - фильера

single-screw extruder - одночервячный экструдер drag pump - тяговый насос

slot - вырез, шлиц, щель 24. stranding - выпуск нити face outting - профилирование

Exercises

I. Translate the following sentences paying attention to the meaning of the word "available" :

1. Mixer manufacturers generally have laboratories available for determining the best type of mixer in combination with a tank.

2. Of all the instruments available a thermometer is the most suitable for measuring temperature.

3. In manufacturing plastics, greatly improved methods are available.

4. All of our available energy hag come from the sun.

5. We must learn to increase the efficiency of our use of fuel and to make available new sources of energy.

6. These tickets are available for 3 days only.

7. What we are interested to know is what fraction of
the available energy we get in the form of useful work.

8. This device is not available for use now.

II. Translate the following sentences. Mind the meaning of the words "should" and "would":

Answer the following questions

en

1. What purposes are agitators Used for?

2. What duties are required of rotating mixers? .

3. How can the best type of a mixer for a given process selected? 4. What factors have to be considered when deciding whether

mixer should be top-entering, bottom-entering, or side-tering?

5. In what cases are baffles used?

6. What types of mixers do you know?

7. How does the Farral continuous mixer operate?

8. Why does this machine require a seconds-stage device

9. What can you say about a single-screw extruder?

be